FormFutura Crystal Flex is the most translucent filament I’ve seen yet. It doesn’t seem to have any color cast so it really is near perfect. Unfortunately FDM printing doesn’t allow for truly clear prints. With any flex filament I recommend a glue stick on a PEI bed. FormFutura sells Crystal filament in 500g sizes on plastic spools.

https://www.formfutura.com/shop/product/crystal-flex-clear-164?category=158

Recommended Print Settings

Temperatures

• Hot End – 240 Celsius
• Bed – 90 Celsius

Speeds

• Print Speed – 50mm/s
• First Layer Speed – 30mm/s
• Perimeter Speed – 30mm/s
• Infill Speed – 60mm/s
• Cooling Fan Speed – 30-80%

Structure

• Perimeters – 2 or 0.8mm – 1mm
• Top and Bottom Layers – 4 to 5 or 1mm
• Infill – 15%

Retraction

• Distance – 0.8mm*
• Speed – 35mm*
• Z-Lift – 0.6mm

Bridging

• Bridge Flow – 85%
• Bridge Speed – 30mm/s
• Bridge Cooling – 80%

Physical

• Bed Adhesion – Glue Stick (Required)
• Nozzle Type – Brass (Standard)
• Enclosure – None

* Values will differ for printers with Bowden extruders